<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var a = 1 + 2;
        var b = 3;
        var c = a + b;

        var d = 'a' + true;
        console.log(d);
    </script>

    <script>
        var a = 1 > 2;
        console.log(a);
        var b = "a" > "b"; //比的asc码,百度搜索asc码表
        console.log(b);
        var c = "1" > "8";
        var d = "80" > "8"; //字符串"10" 先比第一个字符，一样则比第二个（字符串比较的原则）
        console.log(c, d);

        var e = 1 == 2;
        var f = 1 != 2;
        console.log(e,f);

        var g = NaN == NaN;
        var h = Infinity == Infinity;
        var i = undefined == undefined;
        console.log(g,h,i);
    </script>
</body>
</html>